.\" $OpenBSD: BIO_get_data.3,v 1.3 2018/03/23 23:18:17 schwarze Exp $
.\" selective merge up to: OpenSSL e90fc053 Jul 15 09:39:45 2017 -0400
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.\" The original file was written by Matt Caswell <matt@openssl.org>.
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.Dd $Mdocdate: March 23 2018 $
.Dt BIO_GET_DATA 3
.Os
.Sh NAME
.Nm BIO_set_data ,
.Nm BIO_get_data ,
.Nm BIO_set_init ,
.Nm BIO_set_shutdown ,
.Nm BIO_get_shutdown
.Nd manage BIO state information
.Sh SYNOPSIS
.In openssl/bio.h
.Ft void
.Fo BIO_set_data
.Fa "BIO *a"
.Fa "void *ptr"
.Fc
.Ft void *
.Fo BIO_get_data
.Fa "BIO *a"
.Fc
.Ft void
.Fo BIO_set_init
.Fa "BIO *a"
.Fa "int init"
.Fc
.Ft void
.Fo BIO_set_shutdown
.Fa "BIO *a"
.Fa "int shutdown"
.Fc
.Ft int
.Fo BIO_get_shutdown
.Fa "BIO *a"
.Fc
.Sh DESCRIPTION
These functions are mainly useful when implementing a custom BIO.
.Pp
The
.Fn BIO_set_data
function associates the custom data pointed to by
.Fa ptr
with the
.Fa "BIO a" .
This data can subsequently be retrieved via a call to
.Fn BIO_get_data .
This can be used by custom BIOs for storing implementation specific
information.
.Pp
The
.Fn BIO_set_init
function sets the
.Fa init
flag in
.Fa a
to the specified value.
A non-zero value indicates that initialisation is complete,
whilst zero indicates that it is not.
Often initialisation will complete
during initial construction of the BIO.
For some BIOs however, initialisation may not be complete until
additional steps have been taken, for example through calling custom
ctrls.
.Pp
The
.Fn BIO_set_shutdown
and
.Fn BIO_get_shutdown
functions are low-level interfaces to forcefully set and get the
.Fa shutdown
flag of
.Fa a ,
circumventing type-dependent sanity checks,
exclusively intended for implementing a new BIO type.
The
.Fa shutdown
argument must be either
.Dv BIO_CLOSE
or
.Dv BIO_NOCLOSE .
When merely using a
.Vt BIO
object, call
.Xr BIO_set_close 3
and
.Xr BIO_get_close 3
instead.
.Sh RETURN VALUES
.Fn BIO_get_data
returns a pointer to the implementation specific custom data associated
with
.Fa a ,
or
.Dv NULL
if none is set.
.Pp
.Fn BIO_get_shutdown
returns the value previously set with
.Fn BIO_set_shutdown
or with
.Xr BIO_set_close 3 .
.Sh SEE ALSO
.Xr BIO_meth_new 3 ,
.Xr BIO_new 3 ,
.Xr BIO_set_close 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0
and have been available since
.Ox 6.3 .
